1. Field of the Invention
The present invention is generally in the area of stem cell collection, and particularly in the recovery of embryonic-like stem cells and other multipotent stem cells from placentas. These embryonic-like stem cells are derived from the placenta collected after birth. These embryonic-like stem cells have characteristics of embryonic stem cells but are not derived from the embryo.
2. Description of the Background Art
Human stem cells are totipotential or pluripotential precursor cells capable of generating a variety of mature human cell lineages. This ability serves as the basis for the cellular differentiation and specialization necessary for organ and tissue development. Recent success at transplanting such stem cells have provided new clinical tools to reconstitute and/or supplement the bone marrow after myeloablation due to disease, exposure to toxic chemical or radiation. Further evidence exists which demonstrates that stem cells can be employed to repopulate many, if not all, tissues and restore physiologic and anatomic functionality. The application of stem cells in tissue engineering, gene therapy delivery and cell therapeutics is also advancing rapidly.
Obtaining sufficient human stem cells has been problematic for several reasons. First, isolation of normally occurring populations of stem cells in adult tissues has been technically difficult, costly and very limited in quantity. Secondly, procurement of these cells from embryos or fetal tissue including abortuses has raised many ethical and moral concerns. The widely held belief that the human embryo and fetus constitute independent life has justified a moratorium on the use of such sources for any purpose. Alternative sources which do not violate the sanctity of independent life would be essential for further progress in the use of stem cells clinically.
Umbilical cord blood (cord blood) is a known source of hemopoietic pluripotent, progenitor stem cells that are cryopreserved for use in hemopoietic reconstitution. The use of cord blood for this purpose is well known and is becoming a widely used therapeutic procedure. The conventional technique for the collection of cord blood is based on the use of a needle or cannula which is used with the aid of gravity to drain the cord blood from the placenta. Usually the needle or cannula is placed in the umbilical vein and the placenta is gently massaged to aid in draining the cord blood from the placenta. Thereafter the drained placenta has been considered to be of no use and has typically been discarded. A major limitation of stem cell procurement from cord blood has been the frequently inadequate volume of cord blood obtained resulting in insufficient cell numbers to reconstitute bone marrow after transplantation.
Stem cells are in critically short supply. These are important for the treatment of a wide variety of disorders, including malignancies, inborn errors of metabolism, hemoglobinopathies, and immunodeficiences. It would be highly advantageous to have a source of more embryonic stem cells.
Accordingly, it is a primary object of the present invention to provide a method of extracting and recovering hematopoietic stem cells from an exsanguinated placenta.
It is also an object of the invention to provide a method for isolating other embryonic-like and/or omnipotent stem cells from an extractant of a drained placenta.
It is a further object of the invention to provide a method to collect stem cells from the umbilical cord vein, the best source of hemopoietic pluripotent progenitor stem cells.
It is a further object of the present invention to provide a method and means whereby additional embryonic-like stem cells in higher concentrations can be obtained from a drained placenta.
It is a further object of the invention to provide a method of utilizing the isolated and perfused placenta as a bioreactor providing a good environment for the propagation of endogenous cells, including but not limited to lymphocytes and stem cells.
It is a further object of the present invention to provide a method and means whereby stem cells can be obtained many hours following the birth and expulsion of the placenta from the uterus.